共查询到15条相似文献,搜索用时 116 毫秒
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研究了800nm飞秒激光照射下45°高反膜ZrO2-Si O2的破坏及其超快动力学过程。利用原子力显微镜和扫描电镜观察了材料的烧蚀形貌,测量了破坏阈值与脉冲宽度、烧蚀深度与脉冲能量的依赖关系。随着脉冲宽度从50fs增加到900fs,其烧蚀阈值从0.35J/cm2增加到1.78J/cm2。烧蚀深度与激光能流密度近似成对数关系。当激光强度略高于烧蚀阈值时,材料很快被烧蚀到几百纳米,烧蚀深度表现出明显的层状特性。同时,利用建立的抽运探针实验系统,测量了高强度抽运脉冲作用下材料对探针光的反射率随延迟时间的变化,揭示了薄膜烧蚀的超快动力学过程。实验结果表明高反膜表层的材料对烧蚀特性有重要影响。 相似文献
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开展了脉宽为40 fs的不同数量激光脉冲对锗材料的烧蚀效应实验,采用扫描电镜、激光共聚焦显微镜等方法对不同数量的飞秒激光脉冲作用下锗材料表面烧蚀区进行了检测,并对作用后材料烧蚀形貌演化规律进行了分析,初步分析了锗材料烧蚀区周围形成的不同环区的形貌特征及成因,对各环区烧蚀形貌特征随激光作用脉冲数的增加而产生的形貌演化过程进行了观测。并给出单脉冲飞秒激光对锗材料的烧蚀阈值为1.2 J·cm-2,采用激光共聚焦显微镜测得该阈值条件下单个飞秒激光脉冲对锗材料的烧蚀深度约为150 nm。 相似文献
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飞秒激光的波长对SiC材料烧蚀的影响 总被引:10,自引:0,他引:10
利用10倍的显微物镜将近红外飞秒激光脉冲汇聚到宽带隙半导体材料6H SiC的前表面,研究样品的烧蚀及诱导微细结构。用扫描电镜(Scanning electron microscope,SEM)及光学显微镜测量烧蚀斑。利用烧蚀面积与激光脉冲能量的关系确定SiC的烧蚀阈值。给出了SiC样品的烧蚀阈值与飞秒激光波长的依赖关系。实验结果表明,可见光区随波长增加,烧蚀阈值从0.29J/cm2增加到0.67J/cm2;而在近红外区,SiC的烧蚀阈值为0.70J/cm2左右,基本上不随激光波长变化而改变。结合计算结果,可以认为在飞秒激光烧蚀SiC的过程中,在近红外区,光致电离和碰撞电离均起到了重要的作用;而在可见光区,光致电离的作用相对大一些。 相似文献
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采用飞秒激光对氟化钙晶体表面进行加工。通过调控激光参数,采用静止聚焦和动态扫描两种方式在晶体表面加工出一系列微结构(烧蚀孔和烧蚀线)。分别对两种加工方式烧蚀后的氟化钙晶体表面微结构进行系统研究,包括参数依赖关系、材料表面烧蚀阈值等。计算结果表明:在静止聚焦情况下,累积因子为0.0033;在动态扫描情况下,当扫描方向与激光偏振方向垂直或平行时,累积因子分别为0.0043和0.0052。飞秒激光加工过程中的脉冲累积效应能够对晶体的烧蚀产生重要影响。 相似文献
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在超快激光照射过程中,金属靶材的光学性质是动态变化的。采用双温模型与分子动力学结合法,考虑动态和常数光学性质两种情况,对不同脉宽的超快激光照射下铜薄膜的热响应进行了模拟研究。其中,常数光学性质包括由激光沉积能量相等计算得到的等效平均反射率和室温下的吸收系数。结果表明:两种情况下的电子温度和晶格温度均差别较小,尤其是脉宽远小于电子-晶格弛豫时间的飞秒激光; 而当激光脉宽相当于或大于电子-晶格弛豫时间时,如皮秒激光,光学性质的动态变化对材料的熔化和重凝的影响则比较明显。 相似文献
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The selective ablation of thin (∼100 nm) SiO2 layers from silicon wafers has been investigated by applying ultra-short laser pulses at a wavelength of 800 nm with pulse
durations in the range from 50 to 2000 fs. We found a strong, monotonic decrease of the laser fluence needed for complete
ablation of the dielectric layer with decreasing pulse duration. The threshold fluence for 100% ablation probability decreased
from 750 mJ/cm2 at 2 ps to 480 mJ/cm2 at 50 fs. Significant corruption of the opened Si surface has been observed above ∼1200 mJ/cm2, independent of pulse duration. By a detailed analysis of the experimental series the values for melting and breaking thresholds
are obtained; the physical mechanisms responsible for the significant dependence on the laser pulse duration are discussed. 相似文献
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Ablation experiments with femtosecond (fs) laser pulse (pulse duration 37 fs, wavelength 800 nm) on organic polymers have been performed in air. The ablation threshold is found to be only several nanojoules. The diameters of the dots ablated in the organic polymers are influenced by the laser fluence and the number of laser pulses. It is observed that heat is diffused in a threadlike manner in all directions around the central focus region.Explanations of the observed phenomena are presented. A one-dimensional waveguide is also ablated in the organic polymers. 相似文献
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Lithium niobate is praised as silicon in nonlinear optics for its wide usage both in fundamental science and applications
in optics. But its photorefractive effect hinders it from more extensive application in optics. The deadlock has been broken
by doping some metallic elements such as magnesium into the congruent lithium niobate crystal for its high damage resistance.
The single-shot and multi-shot surface ablation experiments by femotosecond laser with the wavelength of 800 nm and the duration
of 80 fs were conducted in the same condition and the ablation threshold fluence was gained for congruent lithium niobate
crystal and 6 mol % Mg-doped lithium niobate crystal. The band gap widening after doping is responsible for the discrepancy
of the ablation thresholds between the two samples. The laser threshold fluence dependence of lasershot number demonstrates
the difference of the accumulation effect. The large reduction of trapping cross section for electrons after heavy doping
of magnesium is focused more to interpret this distinction. 相似文献
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J. Bonse S. Baudach J. Krüger W. Kautek M. Lenzner 《Applied Physics A: Materials Science & Processing》2002,74(1):19-25
We investigated the initial modification and ablation of crystalline silicon with single and multiple Ti:sapphire laser pulses
of 5 to 400 fs duration. In accordance with earlier established models, we found the phenomena amorphization, melting, re-crystallization,
nucleated vaporization, and ablation to occur with increasing laser fluence down to the shortest pulse durations. We noticed
new morphological features (bubbles) as well as familiar ones (ripples, columns). A nearly constant ablation threshold fluence
on the order of 0.2 J/cm2 for all pulse durations and multiple-pulse irradiation was observed. For a duration of ≈100 fs, significant incubation can
be observed, whereas for 5 fs pulses, the ablation threshold does not depend on the pulse number within the experimental error.
For micromachining of silicon, a pulse duration of less than 500 fs is not advantageous.
Received: 4 December 2000 / Revised version: 29 March 2001 / Published online: 20 June 2001 相似文献
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Qinglong Meng Bin Zhang Sencheng Zhong Liguo Zhu 《Applied Physics A: Materials Science & Processing》2016,122(6):582
The damage threshold of lithium niobate crystal under single and multiple femtosecond laser pulses has been studied theoretically and experimentally. Firstly, the model for the damage threshold prediction of crystal materials based on the improved rate equation has been proposed. Then, the experimental measure method of the damage threshold of crystal materials has been given in detail. On the basis, the variation of the damage threshold of lithium niobate crystal with the pulse duration has also been analyzed quantitatively. Finally, the damage threshold of lithium niobate crystal under multiple laser pulses has been measured and compared to the theoretical results. The results show that the transmittance of lithium niobate crystal is almost a constant when the laser pulse fluence is relative low, whereas it decreases linearly with the increase in the laser pulse fluence below the damage threshold. The damage threshold of lithium niobate crystal increases with the increase in the duration of the femtosecond laser pulse. And the damage threshold of lithium niobate crystal under multiple laser pulses is obviously lower than that irradiated by a single laser pulse. The theoretical data fall in good agreement with the experimental results. 相似文献